One of the most important documentaries I've seen in a long time is COWSPIRACY - The Sustainability Secret, a film by a group of young film makers from California. They point out a very large "elephant in the room" that very few people are talking about, because such a vast economic system is behind that "elephant". But everyone should know about it, because it's something we can do, every single day, that can actively make a difference.
Recently the United Nations has recommended a vegan diet as SIGNIFICANT TO ENVIRONMENTAL SUSTAINABILITY. The U.N.! Regardless how people may feel about animals, and the health benefits of a vegan diet, if they care about climate change and a future for their children, I believe this is very important information.
The movie is available on Netflix, and elsewhere.